Conventional stereoscopic image projectors, as shown in FIG. 6, generally includes image-projecting units 1a, 1b each of which includes lamps 4a and 4b, spherical reflecting mirrors 3a and 3b, focusing lens devices 5a and 5b, LCD (Liquid Crystal Display) panels 6a and 6b, and projecting lenses 7a and 7b. The units 1a and 1b are individually driven, in order to match two images and thus produce a stereoscopic image on a screen S. Specifically, producing a focused image from one unit 1a on the screen S to produce a distinct image, and then moving the unit 1b vertically and laterally to produce another image focused overlapping the image from the unit 1b on the screen S to create the stereoscopic effect.
In such a conventional stereoscopic projector, however, optical axes La and Lb of the units 1a and 1b are inclined at a certain angle with respect to the central axis L of screen S, so that left and right images on the screen S are projected in the shape of a trapezoid as shown in FIG. 7. Thereby a keystone phenomenon occurs with the result that the two images are not completely matched in the overlapping arrangement, and thereby distorted. Consequently, such a conventional projector has a disadvantage of increasing the fatigue of viewer's eyes. In addition, there is a disadvantage that matching images on the screen S becomes troublesome and inconvenient, because two image projecting units 1a and 1b are individually driven and adjusted.
It is desired to provide a stereo projection optical system which can overcome the above-described deficiencies.